#include<bits/stdc++.h>
#define ll long long
#define pb push_back
#define ff first
#define ss second
#define mp make_pair
#define sz(x) (int)(x).size()
#define all(x) x.begin(), x.end()
using namespace std;

const char nl='\n';
const int MOD=1000000007;
const int N=1000005;

int n, niz[N];
bool mog[1000005];

int tr = 0;
void solve(){
    scanf("%d", &n);
    for(int i=1;i<=n;i++)
    {
        scanf("%d", &niz[i]);
        mog[niz[i]] = true;
        while (mog[tr])
            tr++;
        printf("%d\n", tr);
    }
}
int main () {
    cin.tie(NULL);
    ios_base::sync_with_stdio(false);

    freopen("prefmex.in", "r", stdin);
    freopen("prefmex.out", "w", stdout);

    int T=1;
    while(T--)
    {
        solve();
    }

    return 0;
}